It was epic in scope, in numbers of people and scale of investment and construction; epic as well in its daring transfer of physical and chemical processes directly from the laboratory to the huge enrichment and separation facilities at Oak Ridge, Tennessee, and Hanford, Washington. I can think of no other major new technical process that has been industrialized in so short a time--testimony to how dangerous the new weapons were understood to be, capable even of turning defeat into victory if it came to that.
Fortunately, it didn't come to that. It came instead to a decision, more controversial now than it was in the summer of 1945, to use the first two bombs against Japanese cities in the hope of shocking the Japanese into surrender before the invasion of their home islands, scheduled for November, took an even greater toll of American and Japanese lives. That decision is discussed in The Manhattan Project by experts; I would only remind you that destroying Japanese cities with firebombing--destruction fully as total as the atomic bombings brought--had been underway for months, and that Hiroshima and Nagasaki would already have been burned out by August 1945 had they not been removed from the U.S. Air Force's target list. The moral decision to use terror bombing against civilian populations had been made two years earlier, in Europe, and it was fully implemented in Japan in the last months of the war, until only cities with less than 50,000 population (excluding those on the atomic bombing target list) remained untouched.
These hard choices and decisions, following as they did from a great, and in the long run humane, work of human collaboration, are much of what gives the Manhattan Project story its almost mythic resonance.
Walter Isaacson calls it "fascinating"; Jennet Conant (whose work appears in the book) calls it "remarkable ... compelling ... and horrifying"; Bruce Babbitt was "enthralled."
